Ki-67 Expression in Benign Breast Ductal Cells Obtained by Random Periareolar Fine Needle Aspiration

Ki-67 expression in ductal cells obtained by random periareolar fine needle aspiration (RPFNA) is currently being used as a response biomarker in phase II breast cancer chemoprevention trials; however, Ki-67 in RPFNA has not been well studied as a risk predictor for cancer, which would support its use as a response indicator. We examined the expression of Ki-67 in RPFNA specimens with hyperplasia ± atypia obtained from 147 women at high risk for development of breast cancer. Median Ki-67 was 1.4% (range 0-24%). Ki-67 was higher in specimens from women